A North Atlantic right whale mother, Wart, and her 3-week-old calf, off the coast of Plymouth Harbor on Tuesday, appear to be healthy, according to scientists.

Bay whales cold, but doing OK

By MARY ANN BRAGG

mbragg@capecodonline.com

January 23, 2013 - 2:00 AM

Correction: Because of a reporting error, the original version of this story had the wrong age for the North Atlantic right whale known as Wart. Experts estimate she is in her early 40s.

PLYMOUTH — A North Atlantic right whale mother and calf are in cold, stressful conditions off the coast of Plymouth Harbor, scientists said Tuesday. But the good news is that Wart, believed to be in her early 40s, and what is believed to be her seventh calf, look healthy.

"She's one of the old-time mommas," Amy Knowlton, a research scientist with the New England Aquarium, said Tuesday.

The mother and 3-week-old calf, first spotted Jan. 12, have been swimming close to the shore from the eastern end of the Cape Cod Canal to the northern edge of Plymouth Harbor. Federal officials are issuing mariner warnings in the region to prevent any possible boat collisions with the pair.

Wart is a heroine of sorts among North Atlantic right whales experts.

She had a calf in 2005 — named Black Heart — and then, starting in 2008, was entangled in rope for two years. In 2010, a team from the Provincetown Center for Coastal Studies used a razor device called a "Gobbler Guillotine" to cut off the rope. Right whale experts worried that her health might have been compromised since she took so long to birth another calf.

"Then she shows up with a calf," Erin Burke, a protected-species specialist with the state Division of Marine Fisheries, said. "So, OK, you're doing OK."

Researchers and conservationists took a boat out Monday to see the pair, and take photographs, water temperature readings, samplings of zooplankton that the whales eat and underwater sound checks. More boat surveys are planned, and scientists hope to take a skin sample from the calf once it reaches its first month to determine its sex and possibly its father.

Knowlton has reviewed researchers' photos to help determine the calf's age and overall health of both marine mammals. Both are in "decent shape," she said.

There are fewer than 500 North Atlantic right whales in the world, so births of the endangered marine mammal are carefully monitored by federal and state officials along with research and conservation groups.

This pair has drawn attention because a mother typically gives birth in warmer waters off the southeastern U.S. coast, and usually wouldn't appear with a calf in northern feeding areas such as Cape Cod Bay until spring.

There were no new sightings of the pair reported by Tuesday afternoon, according to Regina Asmutis-Silvia of Whale and Dolphin Conservation Society, a nonprofit dedicated to the protection of the marine mammals.

"It's not an ideal environment ... the mother and calf can be assumed to be under some kind of stress, and that stress is cold temperature," right whale habitat expert Charles "Stormy" Mayo of the Provincetown center said Tuesday afternoon after analyzing data from the boat survey Monday.

"The calf, without a thick layer of blubber, has got to get a lot of energy from the mother," he said. "It does not mean that they are imperiled. It may mean it's not the best environment."

The earliest recorded sighting of a right whale mother-and-calf pair in Cape Cod Bay is March 26, Mayo said. But research from the past 30 years has raised questions about whether calves have been born in northeastern waters, said Burke.

"We don't see everything that goes on," Burke said. "While very rare, it may not be totally unheard of."

Counting Wart's calf, there have been 16 North Atlantic right whales known to be born in the past two months, according to records of the National Oceanic and Atmospheric Administration. Wart likely gave birth up here, the researchers believe, but the other 15 calves have been recorded in southern birthing waters off the coast of Georgia and Florida. Those whales will eventually migrate north, usually arriving in Cape waters by April.

Water temperatures off the southern coast were about 61 degrees this week, Mayo said, based on information from the New England Aquarium in Boston. The level of zooplankton is generally low in southern waters, but it doesn't matter because whale mothers don't eat while their calves are nursing down south. They instead rely on their large stores of blubber.

In comparison, the water temperature in Plymouth Harbor on Monday was 41 degrees, Mayo said. The cold temperature would likely drain more energy than usual from the mother, and levels of zooplankton were low in the harbor, but it would not necessarily spell doom for the calf.

"These mothers have a huge energy reserve," he said. "We can be sure that wherever she is, she's pumping it out right now."

On Monday, the calf flapped its tiny flippers and was on its side a lot, Burke said. During a 30-minute underwater recording, there were no apparent calls between the two, federal researchers Allison Henry and Denise Risch said.

The relative silence was expected, because there's no need for the mother to call to the calf, given how physically close they were, Henry and Risch said.

"You always knew even if you could see the calf, the mom was right beneath her," Henry said. She estimated they were in water about 25 feet deep.

"Wart is in the best place she can be," Knowlton said. "Already some right whales have been seen feeding in the bay."

If Wart needs to feed, then there is an opportunity in the bay area, she said. There's some concern that as she nurses, Wart could lose body weight to the point where she couldn't nurse her calf, Knowlton said. "The fact is, at 3 weeks old, if it were not thriving, we would see indications of that," she said

Fact Box

LIVING LARGE

Estimated size and weight of the right whale mother and calf in Cape Cod Bay: